A microelectromechanical system (MEMS) is a microelectromechanical device fabricated in a microminiaturized package structure, and the fabricating technique thereof is quite similar to that of integrated circuits (ICs). However, interactions, for example, about mechanics, optics, or magnetic force between the MEMS device and surrounding environment are more than that of the conventional IC. The MEMS device may include micro-sized electromechanical components, such as motors, pumps, valves, switches, capacitors, accelerometers, sensors, capacitive sensors, pixels, microphones, or actuators, etc. The electromechanical components, which are designed based on capacitance principles, usually work out by the coaction between the mechanical structure and the semiconductor device (e.g. IC).
In general, microphones fabricated by adopting the MEMS technology are advantageous in light weight, compact size, and desirable signal quality, and become the mainstream of miniature microphones. Furthermore, due to increasing demands for wide application of the miniature microphones in electronic products such as mobile phones, requirements for sound-receiving quality and integration of the MEMS microphone with the circuit are further highlighted.